Modern vehicles (including but not limited to cars, buses, trains, and planes) consist of many elements, such as sensors, switches, actuators, motors, displays, and entertainment functions. For example, FIG. 1 illustrates an example vehicle assembly including a vehicle 10, a main wiring harness (partial) 20, a mirror motor 30, a driver door controller 40, a window motor 50, a driver door key sensor node and window switch node (inside) 60, a passenger door controller 70, a window motor 80, a passenger door key sensor node and window switch node (inside) 90, a mirror heater 100, a front door 120, and a passenger door 110.
The CAN (controller area network) bus was developed in 1983 to allow the different vehicle modules to communicate. The CAN bus uses four dedicated wires, and an open collector interface so the number of devices it can support on a bus is electrically limited. In modern vehicles there may be more than 70 nodes that need to be connected, and the CAN bus requires multiple bridged CAN networks in order to exceed the electrical limit. This results in additional complexity, expense, and weight.